FIG. 1 is a perspective view showing a configuration of a related crimp terminal described in Patent Document 1, for example.
A crimp terminal 101 includes an electrical connection portion 110 which is to be connected to a terminal of a mating connector in its front portion in a longitudinal direction of the terminal (also in a longitudinal direction of a conductor of an electric wire which is to be connected thereto), includes a conductor crimp portion 111 which is to be crimped around an exposed conductor of an end of the electric wire (not illustrated) behind the electrical connection portion 110, and further includes a coated crimping portion 112 which is to be crimped around an insulation coating portion of the electric wire behind the conductor crimp portion 111. The crimp terminal 101 includes a first joint portion 113, which joins the electrical connection portion 110 and the conductor crimp portion 111 together, between the electrical connection portion 110 and the conductor crimp portion 111, and includes a second joint portion 114, which joins the conductor crimp portion 111 and the coated crimping portion 112 together, between the conductor crimp portion 111 and the coated crimping portion 112.
The conductor crimp portion 111 is formed in a substantially U-shaped cross section from: a bottom plate 111A; and a pair of conductor crimping pieces 111B, 111B which extend upwardly from both right and left side edges of the bottom plate 111A, and which are to be crimped around the conductor of the electric wire disposed on an inner surface of the bottom plate 111A. The coated crimping portion 112 is formed in a substantially U-shaped cross section from: a bottom plate 112A; and a pair of coated crimping pieces 112B, 112B which extend upwardly from both right and left side edges of the bottom plate 112A, and which are to be crimped around the electric wire (a part of the electric wire which is covered with an insulation coating) disposed on an inner surface of the bottom plate 112A.
The first joint portion 113 and the second joint portion 114 which are located in the front side and rear side of the conductor crimp portion 111 are formed in a substantially U-shaped cross section from: bottom plates 113A, 114A; and low side plates 113B, 114B which are erected upwardly from both right and left side edges of the bottom plates 113A, 114A, respectively.
Then, bottom plates ranging from a bottom plate (not illustrated) of the electrical connection portion 110 in the front to the bottom plate of the coated crimping portion 112 in the rearmost (that is to say, the bottom plate 113A of the first joint portion 113, the bottom plate 111A of the conductor crimp portion 111, the bottom plate 114A of the second joint portion 114, and the bottom plate 112A of the coated crimping portion 112) are formed continuously like a single strip-shaped plate. Front and rear ends of the low side plates 113B of the first joint portion 113 continue, respectively, to lower half portions of rear ends of side plates (whose reference numerals are omitted) of the electrical connection portion 110 and front ends of the conductor crimping pieces 111B of the conductor crimp portion 111. Front and rear ends of the low side plates 114B of the second joint portion 114 continue, respectively, to lower half portions of rear ends of the conductor crimping pieces 111B of the conductor crimp portion 111 and front ends of the coated crimping pieces 112B of the coated crimping portion 112.
Multiple recessed groove-shaped serrations 120, which extend in a direction orthogonal to the direction in which the conductor of the electric wire extends (i.e., the longitudinal direction of the terminal), are provided in an inner surface 111R, out of the inner surface 111R and an outer surface 111S of the conductor crimp portion 111, which comes in contact with the conductor of the electric wire.
FIG. 2 is a detailed view of the serrations 120 formed in an inner surface of the conductor crimp portion 111. FIG. 2(a) is a plan view showing a development of the conductor crimp portion 111; FIG. 2(b) is a cross-sectional view of the serrations 120 taken along a line indicated by arrows IIb-IIb in FIG. 2(a); and FIG. 2(c) is an enlarged view of a part IIc in FIG. 2(b).
The cross-sectional shape of each recessed groove-shaped serration 120 is a rectangular shape or a reversed trapezoidal shape. An inner bottom surface 120A is formed substantially in parallel with the outer surface 111S of the conductor crimp portion 111. Inner corner portions 120C, where the inner bottom surface 120A intersects inner side surfaces 120B, are formed as angular portions where planes intersect each other. Hole edges 120D, where the inner side surfaces 120B intersect the inner surface 111R of the conductor crimp portion 111, are formed as edges.
As shown in FIG. 3, the conductor crimp portion 111 including the serrations 120 is generally manufactured by press working by use of a die 200 (which is practically referred to as a serration die which is to be attached to an upper half of a press die) having raised portions 220 located at positions respectively corresponding to the recessed groove-shaped serrations 120.
As shown in FIG. 4, since the raised portions 220 are linear in shape, the die 200 of this case is manufactured by performing grinding on an upper surface of a block 210 by use of a rotary grinding wheel 250. FIG. 5 shows an outer appearance of the die 200.
To crimp the conductor crimp portion 111 of the crimp terminal 101 configured as described above around a conductor in an end of an electric wire, the crimp terminal 101 is mounted on a mount surface (upper surface) of a lower half die (anvil) which is not illustrated, and the conductor of the electric wire is mounted on an upper surface of the bottom plate 111A while inserted between the conductor crimping pieces 111A of the conductor crimp portion 111. Then, an upper half die (crimper) is lowered relative to the lower half die, and thereby top end sides of the conductor crimping pieces 111B are gradually folded toward the inside thereof by a guide slope of the upper half die.
Subsequently, the upper half die (crimper) is further lowered relative to the lower half die. Finally, the top ends of the conductor crimping pieces 111B are rounded in such a way as to be folded toward the conductor by a curved surface continuous from the guide slope to a central angle portion of the upper half die, the top ends of the conductor crimping pieces 111B dig into the conductor while rubbing against each other, and thereby the conductor crimping pieces 111B are crimped in such a way that the conductor is wrapped by the conductor crimping pieces 111B.
Through the operations described above, the conductor crimp portion 111 of the crimp terminal 101 can be connected to the conductor of the electric wire by compression attachment. As for the coated crimping portion 112, the coated crimping pieces 112B are similarly crimped around an insulation coating portion of the electric wire by gradually bending the coated crimping pieces 112B toward the inside thereof by use of the lower half die and the upper half die. Thereby, the crimp terminal 101 can be electrically and mechanically connected to the electric wire.
When the compression attachment is performed by crimping as described above, the conductor of the electric wire enters the serrations 120 in the inner surface of the conductor crimp portion 111 while deforming plastically due to a pressure force. Thus, the connection between the crimp terminal 101 and the electric wire is strengthened.